Antibiotic resistance

Question 1

What does the term “antibiotic era” refer to?

Answer 1

The time since the widespread availability of antibiotics to treat infection

Question 2

What does the term “post-antibiotic era” refer to?

Answer 2

The time after widespread antibiotic resistance has reduced the availability of antibiotics to treat infection

Question 3

What are the risks of empiric therapy?

Answer 3

Under-treatment

Excessive use of broad-spectrum antibiotics

Question 4

What are the risks of targeted therapy?

Answer 4

Requires use of alternatives which may be expensive, last-line or toxic

Question 5

What are the reasons for sensitivity testing?

Answer 5

Enable targeted therapy
Explain treatment failures
Provide alternative antibiotics in case of failure or side effects
Provide alternative oral antibiotics when IV therapy is no longer required

Question 6

What two types of media can be used in screening?

Answer 6

Solid media - disc susceptibility testing

Liquid media - microtitre plate susceptibility testing

Question 7

What are the 6 principle mechanisms of antibiotic resistance?

Answer 7

1. No target therefore no effect
2. Reduced permeability so drug can’t get in
3. Altered target so no effect of drug
4. Over-expression of target so effect is diluted
5. Enzymatic degradation so drug is destroyed
6. Efflux pump so drug is expelled

Question 8

What makes bacteria resistant to vancomycin?

Answer 8

Gram-negative bacteria reduce permeability so vancomycin cannot enter the cell

Question 9

What makes bacteria resistant to gentamicin?

Answer 9

Uptake of aminoglycosides requires O2 dependent active transport mechanism - reduced permeability of the cell